95 research outputs found
Intelligent-Reflecting-Surface-Assisted UAV Communications for 6G Networks
In 6th-Generation (6G) mobile networks, Intelligent Reflective Surfaces
(IRSs) and Unmanned Aerial Vehicles (UAVs) have emerged as promising
technologies to address the coverage difficulties and resource constraints
faced by terrestrial networks. UAVs, with their mobility and low costs, offer
diverse connectivity options for mobile users and a novel deployment paradigm
for 6G networks. However, the limited battery capacity of UAVs, dynamic and
unpredictable channel environments, and communication resource constraints
result in poor performance of traditional UAV-based networks. IRSs can not only
reconstruct the wireless environment in a unique way, but also achieve wireless
network relay in a cost-effective manner. Hence, it receives significant
attention as a promising solution to solve the above challenges. In this
article, we conduct a comprehensive survey on IRS-assisted UAV communications
for 6G networks. First, primary issues, key technologies, and application
scenarios of IRS-assisted UAV communications for 6G networks are introduced.
Then, we put forward specific solutions to the issues of IRS-assisted UAV
communications. Finally, we discuss some open issues and future research
directions to guide researchers in related fields
IRS-assisted UAV Communications: A Comprehensive Review
Intelligent reflecting surface (IRS) can smartly adjust the wavefronts in
terms of phase, frequency, amplitude and polarization via passive reflections
and without any need of radio frequency (RF) chains. It is envisaged as an
emerging technology which can change wireless communication to improve both
energy and spectrum efficiencies with low energy consumption and low cost. It
can intelligently configure the wireless channels through a massive number of
cost effective passive reflecting elements to improve the system performance.
Similarly, unmanned aerial vehicle (UAV) communication has gained a viable
attention due to flexible deployment, high mobility and ease of integration
with several technologies. However, UAV communication is prone to security
issues and obstructions in real-time applications. Recently, it is foreseen
that UAV and IRS both can integrate together to attain unparalleled
capabilities in difficult scenarios. Both technologies can ensure improved
performance through proactively altering the wireless propagation using smart
signal reflections and maneuver control in three dimensional (3D) space. IRS
can be integrated in both aerial and terrene environments to reap the benefits
of smart reflections. This study briefly discusses UAV communication, IRS and
focuses on IRS-assisted UAC communications. It surveys the existing literature
on this emerging research topic and highlights several promising technologies
which can be implemented in IRS-assisted UAV communication. This study also
presents several application scenarios and open research challenges. This study
goes one step further to elaborate research opportunities to design and
optimize wireless systems with low energy footprint and at low cost. Finally,
we shed some light on future research aspects for IRS-assisted UAV
communication
Trajectory and power design for aerial CRNs with colluding eavesdroppers
Unmanned aerial vehicles (UAVs) can provide wireless access services to
terrestrial users without geographical limitations and will become an essential
part of the future communication system. However, the openness of wireless
channels and the mobility of UAVs make the security of UAV-based communication
systems particularly challenging. This work investigates the security of aerial
cognitive radio networks (CRNs) with multiple uncertainties colluding
eavesdroppers. A cognitive aerial base station transmits messages to cognitive
terrestrial users using the spectrum resource of the primary users. All
secondary terrestrial users and illegitimate receivers jointly decode the
received message. The average secrecy rate of the aerial CRNs is maximized by
jointly optimizing the UAV's trajectory and transmission power. An iterative
algorithm based on block coordinate descent and successive convex approximation
is proposed to solve the non-convex mixed-variable optimization problem.
Numerical results verify the effectiveness of our proposed algorithm and show
that our scheme improves the secrecy performance of airborne CRNs.Comment: 10 pages, 7 figures.submitted to the IEEE journal for revie
Performance analysis of Unmanned Aerial Vehicles-enabled Wireless Networks
University of Technology Sydney. Faculty of Engineering and Information Technology.As an indispensable part of mobile communication systems, Unmanned Aerial Vehicles (UAVs) can be leveraged to complement terrestrial networks by providing coverage to areas where infrastructures are scarce. Equipped with self-navigation and strong automation, UAVs have extensive applications to environmental monitoring, disaster recovery, search and rescue, owing to their excellent agility and autonomy. As a result, an increasing demand arises for ubiquitous connectivity and reliable communication for data exchange between UAVs, and between UAVs and ground stations. Since UAVs operate in three-dimensional (3D) space with strong manoeuvrability, random trajectories and wireless propagation environment can pose significant challenges to the study on coverage and capacity of UAV networks. On the other hand, UAVs are increasingly posing threats to information security. UAVs can be potentially used to eavesdrop and jam wireless transmissions between legitimate terrestrial transceivers. It is of practical interest to understand the robustness of terrestrial wireless communications under exposure to new threats from aerial adversaries. This thesis studies the coverage and capacity, including secure coverage and secrecy capacity, of UAV-enabled wireless networks with UAVs flying under 3D random trajectories based on stochastic geometry and measure convergence theory. The detailed contributions of this thesis are summarised as:
• Capacity analysis of UAV networks under random trajectories. We geometrically derive probability distributions of UAV-to-UAV distances and closed-form bounds for the capacity can be obtained by exploiting the Jensen's inequality. We extrapolate the idea to dense UAV networks and analyse the impact of network densification and imperfect channel state information on the capacity.
• Connectivity analysis of uncoordinated UAV swarms. New closed-form bounds are derived for the outage probability of individual UAVs, and broadcast connectivity of each UAV which evaluates the reliability of broadcast across the swarm. The qualifying conditions of the bounds on 3D coverage and impact of ground interference on the outage are identified.
• Secure connectivity analysis in UAV networks. We propose a trust model based on UAVs’ behaviour and mobility pattern and characteristics of inter-UAV channels. We derive analytical expressions of both physical and secure connectivity probabilities with/without considering Doppler shift.
• Secrecy capacity analysis against aerial eavesdroppers. We analyse ergodic and ϵ-outage secrecy capacities of ground link in the presence of cooperative aerial eavesdroppers. The “cut-off” density of eavesdroppers under which the secrecy capacities vanish is identified. By decoupling the analysis of random trajectories from random channel fading, closed-form approximations with almost sure convergence to the secrecy capacities are devised
Hybrid satellite–terrestrial networks toward 6G : key technologies and open issues
Future wireless networks will be required to provide more wireless services at higher data rates and with global coverage. However, existing homogeneous wireless networks, such as cellular and satellite networks, may not be able to meet such requirements individually, especially in remote terrain, including seas and mountains. One possible solution is to use diversified wireless networks that can exploit the inter-connectivity between satellites, aerial base stations (BSs), and terrestrial BSs over inter-connected space, ground, and aerial networks. Hence, enabling wireless communication in one integrated network has attracted both the industry and the research fraternities. In this work, we provide a comprehensive survey of the most recent work on hybrid satellite–terrestrial networks (HSTNs), focusing on system architecture, performance analysis, design optimization, and secure communication schemes for different cooperative and cognitive HSTN network architectures. Different key technologies are compared. Based on this comparison, several open issues for future research are discussed
Self-Evolving Integrated Vertical Heterogeneous Networks
6G and beyond networks tend towards fully intelligent and adaptive design in
order to provide better operational agility in maintaining universal wireless
access and supporting a wide range of services and use cases while dealing with
network complexity efficiently. Such enhanced network agility will require
developing a self-evolving capability in designing both the network
architecture and resource management to intelligently utilize resources, reduce
operational costs, and achieve the coveted quality of service (QoS). To enable
this capability, the necessity of considering an integrated vertical
heterogeneous network (VHetNet) architecture appears to be inevitable due to
its high inherent agility. Moreover, employing an intelligent framework is
another crucial requirement for self-evolving networks to deal with real-time
network optimization problems. Hence, in this work, to provide a better insight
on network architecture design in support of self-evolving networks, we
highlight the merits of integrated VHetNet architecture while proposing an
intelligent framework for self-evolving integrated vertical heterogeneous
networks (SEI-VHetNets). The impact of the challenges associated with
SEI-VHetNet architecture, on network management is also studied considering a
generalized network model. Furthermore, the current literature on network
management of integrated VHetNets along with the recent advancements in
artificial intelligence (AI)/machine learning (ML) solutions are discussed.
Accordingly, the core challenges of integrating AI/ML in SEI-VHetNets are
identified. Finally, the potential future research directions for advancing the
autonomous and self-evolving capabilities of SEI-VHetNets are discussed.Comment: 25 pages, 5 figures, 2 table
A Prospective Look: Key Enabling Technologies, Applications and Open Research Topics in 6G Networks
The fifth generation (5G) mobile networks are envisaged to enable a plethora
of breakthrough advancements in wireless technologies, providing support of a
diverse set of services over a single platform. While the deployment of 5G
systems is scaling up globally, it is time to look ahead for beyond 5G systems.
This is driven by the emerging societal trends, calling for fully automated
systems and intelligent services supported by extended reality and haptics
communications. To accommodate the stringent requirements of their prospective
applications, which are data-driven and defined by extremely low-latency,
ultra-reliable, fast and seamless wireless connectivity, research initiatives
are currently focusing on a progressive roadmap towards the sixth generation
(6G) networks. In this article, we shed light on some of the major enabling
technologies for 6G, which are expected to revolutionize the fundamental
architectures of cellular networks and provide multiple homogeneous artificial
intelligence-empowered services, including distributed communications, control,
computing, sensing, and energy, from its core to its end nodes. Particularly,
this paper aims to answer several 6G framework related questions: What are the
driving forces for the development of 6G? How will the enabling technologies of
6G differ from those in 5G? What kind of applications and interactions will
they support which would not be supported by 5G? We address these questions by
presenting a profound study of the 6G vision and outlining five of its
disruptive technologies, i.e., terahertz communications, programmable
metasurfaces, drone-based communications, backscatter communications and
tactile internet, as well as their potential applications. Then, by leveraging
the state-of-the-art literature surveyed for each technology, we discuss their
requirements, key challenges, and open research problems
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